SECURITIES - Securities in Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	$ 507,487	$ 587,315
Gross Unrealized Losses, Less than 12 Months	(11,912)	(9,756)
Fair Value, Less than 12 Months	495,575	577,559
Amortized Cost, More than 12 Months	109,352	29,526
Gross Unrealized Losses, More than 12 Months	(3,906)	(643)
Fair Value, More than 12 Months	105,446	28,883
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	5,061	3,520
Gross Unrealized Losses, Less than 12 Months	(73)	(29)
Fair Value, Less than 12 Months	4,988	3,491
Amortized Cost, More than 12 Months	6,221	6,265
Gross Unrealized Losses, More than 12 Months	(290)	(161)
Fair Value, More than 12 Months	5,931	6,104
SBA guaranteed securities
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	80,381	76,603
Gross Unrealized Losses, Less than 12 Months	(1,567)	(948)
Fair Value, Less than 12 Months	78,814	75,655
Mortgage-backed securities issued by U.S. government agencies or sponsored enterprises: residential
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	232,454	192,105
Gross Unrealized Losses, Less than 12 Months	(5,489)	(1,608)
Fair Value, Less than 12 Months	226,965	190,497
Amortized Cost, More than 12 Months	3,814	9,152
Gross Unrealized Losses, More than 12 Months	(50)	(93)
Fair Value, More than 12 Months	3,764	9,059
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	2,777	1,086
Gross Unrealized Losses, Less than 12 Months	(45)	(9)
Fair Value, Less than 12 Months	2,732	1,077
Amortized Cost, More than 12 Months	6,221	6,265
Gross Unrealized Losses, More than 12 Months	(290)	(161)
Fair Value, More than 12 Months	5,931	6,104
Mortgage-backed securities issued by U.S. government agencies or sponsored enterprises: commercial
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	65,920	65,986
Gross Unrealized Losses, Less than 12 Months	(1,371)	(500)
Fair Value, Less than 12 Months	64,549	65,486
Collateralized mortgage obligations issued by U.S. government agencies or sponsored enterprises: residential
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	92,664	210,034
Gross Unrealized Losses, Less than 12 Months	(2,436)	(6,183)
Fair Value, Less than 12 Months	90,228	203,851
Amortized Cost, More than 12 Months	105,538	9,037
Gross Unrealized Losses, More than 12 Months	(3,856)	(251)
Fair Value, More than 12 Months	101,682	8,786
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	2,284	2,434
Gross Unrealized Losses, Less than 12 Months	(28)	(20)
Fair Value, Less than 12 Months	2,256	2,414
Amortized Cost, More than 12 Months	0
Gross Unrealized Losses, More than 12 Months	0
Fair Value, More than 12 Months	0
Collateralized mortgage obligations issued by U.S. government agencies or sponsored enterprises: commercial
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	36,068	36,151
Gross Unrealized Losses, Less than 12 Months	(1,049)	(472)
Fair Value, Less than 12 Months	$ 35,019	35,679
Obligations of municipal subdivisions
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months		6,436
Gross Unrealized Losses, Less than 12 Months		(45)
Fair Value, Less than 12 Months		6,391
CRA qualified investment fund
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, More than 12 Months		11,337
Gross Unrealized Losses, More than 12 Months		(299)
Fair Value, More than 12 Months		$ 11,038